Cooling plate and method for manufacturing a cooling plate

ABSTRACT

The present invention relates to a cooling plate for use in the inner lining of metallurgical furnaces, especially smelting furnaces or shaft furnaces, and relates to a method for manufacturing a cooling plate. The cooling plate has a plate member, which is made of a copper material, and has integrated coolant channels. To manufacture the cooling plate, a raw ingot is provided, which is equipped with channels, and has a starting thickness that is greater than the final thickness of the plate member. The raw ingot is then deformed in a rolling step to reduce the starting thickness to the final thickness of the plate member and to deform the cross-sections of the channels. In this connection, the coolant channels obtain circularly oblong, final cross-sections.

FIELD OF THE INVENTION

[0001] The present invention relates to a cooling plate and a method formanufacturing such a cooling plate for use in the inner lining ofmetallurgical furnaces, especially in smelting furnaces or shaftfurnaces.

BACKGROUND OF THE INVENTION

[0002] For purposes of thermal insulation, metallurgical furnaces areprovided with an interchangeable, metallic inner lining, on whichinsulating materials made of a fireproof material, such as fireproofclay, can be attached. The prevailing temperatures inside the furnaceare so high, that the lining must be cooled. Cooling plates havingintegrated coolant channels are used in this connection. Such coolingplates are usually situated between the furnace shell and the furnacebrick lining, and connected to the cooling system of the furnace. As arule, the sides of the cooling plates facing the interior of the furnaceare provided with fireproof material.

[0003] Cooling plates are known, in which the coolant channels areformed by cast-iron pipes. These cooling plates do not effectivelydissipate heat. In part this is because of the low thermal conductivityof cast iron. Additionally, effective heat dissipation may be preventedby the resistance between the cooling pipes and the plate member causedby an oxide layer or an air gap.

[0004] Copper and copper alloys have a considerably better thermalconductivity than cast iron. In this context, DE 29 07 5 11 C2 describesa cooling plate for shaft furnaces, which is made of copper or alow-alloyed copper alloy, and is manufactured from a forged or rolledcopper block. In this type of construction, coolant channels produced bymechanical deep-hole drilling are situated in the interior of thecooling plate. The coolant channels introduced into the cooling plateare sealed by soldering in or welding in screw caps. Inlet boreholes,which lead to the coolant channels, and are welded or soldered toconnecting pieces necessary for coolant supply or removal, are situatedon the back of the cooling plate.

[0005] In addition, the related art of DE 198 01 425 A1 provides for theintroduction of coolant channels into a cooling plate by mechanicallyremoving material, and provides for covering the resulting channelpattern with a covering plate. To this end, the covering plate must beattached to the cooling plate, so as to form a seal. However, thisprocedure is particularly disadvantageous because of the necessarywelding steps.

[0006] Coolant channels that are not round, e.g., channels that haveoval or oblong cross-sections, have proven themselves reliable, becausethey provide a larger surface for transferring heat. Cast coolingplates, which are made of a copper material and have non-circularcooling channels, are known in this context. However, these have thedisadvantage of the material being coarse-grained and non-uniform. Thisresults in a poor thermal conductivity and the danger of early materialfatigue. Furthermore, it is disadvantageous that structural defects ofthe material or damage to the material, such as microcracks on the castcooling plate, are difficult to detect.

SUMMARY OF THE INVENTION

[0007] The object of the present invention is to provide a high-qualitycooling plate having an increased cooling effect and a high efficiency,as well as to provide a method for cost-effectively manufacturing acooling plate having coolant channels.

[0008] According to one embodiment of the invention, a cooling plate isprovided for use in the inner lining of metallurgical furnaces,especially smelting or shaft furnaces. The cooling plate has a platemember that is made of a copper material having a fine-grained structurepossessing an average particle size of less than 10 mm. The plate memberhas integrated coolant channels. The thickness of the plate member isreduced by machining the final cross sections of the coolant channels.

[0009] As for manufacture of the cooling plate, according to oneembodiment of the invention, a method is provided including a number ofsteps. Initially, a raw ingot is provided that is made of a coppermaterial. The ingot has a starting thickness that is greater than afinal thickness of the plate member. The starting thickness of the rawingot is reduced to the final thickness of the plate member, using atleast one forming step. Coolant channels are produced in the raw ingotor the plate member prior to attaining the final thickness.

[0010] The present invention is described in detail below, using anexemplary embodiment represented in the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 is a perspective view of a cooling plate, according to oneembodiment of the invention; and

[0012]FIG. 2 is a schematic of the method sequence in the production ofa cooling plate shown in FIG. 1, using three manufacturing steps.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0013]FIG. 1 shows a perspective view of a cooling plate 1 for use inthe inner lining of metallurgical furnaces, especially smelting or shaftfurnaces such as blast furnaces, reduction systems, or electric-arcfurnaces.

[0014] Cooling plate 1 includes a plate member 2 made of copper or acopper alloy, into which oval (circularly oblong) coolant channels 3 areintegrated. The copper material of plate member 2 has a fine-grainedstructure possessing an average particle size of less than 10 mm. Aparticle size less than 5 mm, preferably between 0.005 mm and 2 mm, isconsidered especially advantageous.

[0015] In one embodiment of the invention, a first side 4 of platemember 2 has grooves 5, which are subsequently introduced into platemember 2, in order to accommodate fireproof material.

[0016] Cooling plate 1 of the present invention distinguishes itself byimproved cooling and a more uniform heating profile on the inner side ofthe furnace, i.e., on the surface facing the molten mass. Thefine-grained structure improves the thermal conductivity considerably. Areduction in the wall thickness of cooling plate 1 is possible incombination with the final coolant-channel cross-sections, which are, inparticular, circularly oblong. The cooling effect is considerablyimproved. In addition, material savings can be achieved.

[0017] Plate member 2 can be made of a kneaded copper material (or otherforgeable alloy) having a fine-grained structure. However, rolled orcast material is also conceivable. Although it is theoretically possibleto form the copper material hot, the present invention prefers acombined cold/hot forming, in particular a reduction in thickness, usingrolling.

[0018] In accordance with a preferred embodiment of the invention,coolant channels 3 of plate member 2, whose thickness has been reduced,have an oval or circularly oblong, final cross-section. This helps toensure that the heat-transfer surface is optimized for removing heatfrom the cooling plate.

[0019] The manufacture of plate member 2 is shown schematically in FIG.2. The letter “A” indicates the initial state, and the letter “E”represents the final state. Accordingly, a raw ingot 6 of coppermaterial is initially provided, which has a starting thickness greaterD₁ than the final thickness D₂ of plate member 2. Raw ingot 6 can bemade of a forgeable alloy, a cast material, or a rolled material.Channels 7 are mechanically drilled into raw ingot 6, using deep-holedrilling. One can see that channels 7 essentially have circularcross-sections in initial state A.

[0020] The thickness of raw ingot 6 is then reduced by at least oneforming step as shown in the secondary state indicated by the letter“B”, and indeed, to the final thickness D₂ of plate member 2. Thereduction can be achieved by rolling, forging, extrusion, or pressing.It is also conceivable to combine these types of methods. Coolantchannels Q₁ are introduced into raw ingot 6 or plate member 2 prior toattaining the final thickness D₂. Thus, coolant channels Q₁ can alreadybe in raw ingot 6 to begin with, or they can be produced in the courseof reducing the thickness. In this connection, it is conceivable tomanufacture them in steps, while simultaneously changing theircross-sections.

[0021] It is understood that raw ingot 6 has a relatively coarse grainstructure. In the rolling operation which has at least one stage,starting thickness D₁ of raw ingot 6 is reduced to final thickness D₂ ofplate member 2. This rolling operation deforms cross-sections Q₁ ofchannels 7 into final cross-sections Q₂ which, as mentioned above, arepreferably oval, and therefore, circularly oblong. During roll-forming,or a kneading step, plate member 2 obtains a fine-grained structure inthe previously mentioned particle-size range.

[0022] In the end, plate member 2 whose thickness is reduced to finalthickness D₂ can be examined for structural weak points or defects orpossible damage, using ultrasonic material testing. Thus, weak pointscan be detected early, without causing breakdowns and disadvantageousoperating stoppages in the plant.

[0023] In one embodiment of the invention, channels 7 having a circularcross-section are introduced into raw ingot 6 or plate member 2 prior toattaining the final thickness. Channels 7 can be produced using allknown methods. If raw ingot 6 or plate member 2 is then deformed to thefinal thickness, the cross-sections of channels 7 are likewise deformed,and indeed, into the shape of an oval, and consequently, into the shapeof an elongated circle. These cross-sections contribute to animprovement in the thermal conductivity.

[0024] In a particularly advantageous manufacturing step, the startingthickness of raw ingot 6 is initially reduced by cold rolling. In thismanner, the copper material obtains a recrystallized, fine-grainedstructure, in which the typical, solidified structure of the cast copperof the ingot is substantially or completely eliminated. Channels, whosecross-sections are circular, are subsequently introduced into the rawingot having a reduced thickness. The thickness of this raw ingot isthen reduced to the final thickness in at least one working step, usinghot rolling, the circular cross-sections of the channels being deformedinto oval coolant-channel cross-sections that are advantageous from thestandpoint of heat transfer.

[0025] Channels 7 in raw ingot 6 or plate member 2 can be drilledmechanically, using deep-hole drilling. However, it is also conceivablefor the channels to be already cast in raw ingot 6.

[0026] The method allows the cost-effective manufacture of high-qualitycooling plate 1, which has high efficiency improved cooling, along witha uniform heat profile of the surfaces acted upon by heat. In thismanner, it is possible to reduce the wall thickness of a cooling plate 1in comparison with conventional cooling plates having a coarse-grainedstructure. This results in material and cost savings.

[0027] Apart from the advantages of being efficient and inexpensive froma production standpoint, the method yields high-quality cooling plate 1having plate member 2 that is distinguished by a structure possessing anaverage particle size of less than 10 mm. As mentioned above, theforming can achieve an even finer structure having particle sizesbetween 0.005 mm and 2 mm.

What is claimed is:
 1. A cooling plate comprising: a plate member madeof a copper material having a fine-grained structure possessing anaverage particle size of less than 10 mm, the plate member havingintegrated coolant channels, wherein the thickness of the plate memberis reduced by machining the final cross-sections of the coolantchannels.
 2. The cooling plate as recited in claim 1 , wherein theparticle size is less than 5 mm and is preferably between 0.005 mm and 2mm.
 3. The cooling plate as recited in claim 1 , wherein the finalcross-sections of the coolant channels are oval.
 4. The cooling plate asrecited in one of claim 1 , wherein a first side of the plate member hasgrooves for accommodating fireproof material.
 5. A method formanufacturing a cooling plate having a plate member, comprising thesteps of: initially providing a raw ingot made of a copper material, theraw ingot having a starting thickness greater than a final thickness ofthe plate member; reducing the starting thickness of the raw ingot tothe final thickness of the plate member, using at least one formingstep; and producing coolant channels in one of the raw ingot and theplate member prior to attaining the final thickness.
 6. The method asrecited in claim 5 , wherein the coolant channels have circularcross-sections prior to the reducing step, the coolant channels aredeformed in response to the thickness of the plate member being reducedto the final thickness, so that the coolant channels have ovalcross-sections.
 7. The method as recited in claim 5 , wherein the stepof reducing the starting thickness of a raw ingot is accomplished bycold rolling; the step of producing channels having circularcross-sections is subsequent to the rolling, the channels having acircular cross-section; and the step of reducing continues to reduce theingot to the final thickness of the plate member, while the channels aredeformed into coolant channels having oval cross-sections.
 8. The methodas recited in claim 5 , wherein the channels having circularcross-sections are mechanically drilled into one of the raw ingot andthe plate member, using deep-hole drilling.
 9. The method as recited inclaim 5 , wherein the channels are cast into the raw ingot.